Satellites
A satellite is defined as any object that orbits any other object. Satellites can be celestial, such as a moon orbiting a planet in the solar system, or a planet in the solar system orbiting the sun. Satellites can also be man-made. Man-made satellites are typically launched into outer space from earth to collect data, photos and other information about Earth and all the many things that exist around it. From studying outer space and Earth’s atmosphere to tracking weather patterns and acquiring intelligence, satellites illuminate us with vital information and visual imagery that can not be captured in any other manner. Stay up to date with the latest satellite system information and news. Whether you’re interested in NASA and the Mars Renaissance Orbiter, which was the most recent satellite to visit the red planet, or the on-going global race to further research and explore the moon, our diverse satellite images, articles and other news features will expose you to distant places, planets and infinite possibilities for learning more about this expansive galaxy we call home. Begin your exploration of space today with our interactive features, real satellite photos and informative articles below. History Early conceptions The first fictional depiction of a satellite being launched into orbit is a short story by Edward Everett Hale, The Brick Moon. The story is serialized in The Atlantic Monthly, starting in 1869.12 The idea surfaces again in Jules Verne's The Begum's Millions (1879). In 1903 Konstantin Tsiolkovsky (1857–1935) published The Exploration of Cosmic Space by Means of Reaction Devices (in Russian: Исследование мировых пространств реактивными приборами), which is the first academic treatise on the use of rocketry to launch spacecraft. He calculated the orbital speed required for a minimal orbit around the Earth at 8 km/s, and that a multi-stage rocket fueled by liquid propellants could be used to achieve this. He proposed the use of liquid hydrogen and liquid oxygen, though other combinations can be used. In 1928 Slovenian Herman Potočnik (1892–1929) published his sole book, The Problem of Space Travel — The Rocket Motor (German: Das Problem der Befahrung des Weltraums — der Raketen-Motor), a plan for a breakthrough into space and a permanent human presence there. He conceived of a space station in detail and calculated its geostationary orbit. He described the use of orbiting spacecraft for detailed peaceful and military observation of the ground and described how the special conditions of space couldn't be useful for scientific experiments. The book described geostationary satellites (first put forward by Tsiolkovsky) and discussed communication between them and the ground using radio, but fell short of the idea of using satellites for mass broadcasting and as telecommunications relays. In a 1945 Wireless World article the English science fiction writer Arthur C. Clarke (1917-2008) described in detail the possible use of communications satellites for mass communications.3 Clarke examined the logistics of satellite launch, possible orbits and other aspects of the creation of a network of world-circling satellites, pointing to the benefits of high-speed global communications. He also suggested that three geostationary satellites would provide coverage over the entire planet. History of artificial satellites The first artificial satellite was Sputnik 1, launched by the Soviet Union on 4 October 1957, and initiating the Soviet Sputnik program, with Sergei Korolev as chief designer and Kerim Kerimov as his assistant.4 This in turn triggered the Space Race between the Soviet Union and the United States. Sputnik 1 helped to identify the density of high atmospheric layers through measurement of its orbital change and provided data on radio-signal distribution in the ionosphere. Because the satellite's body was filled with pressurized nitrogen, Sputnik 1 also provided the first opportunity for meteoroid detection, as a loss of internal pressure due to meteoroid penetration of the outer surface would have been evident in the temperature data sent back to Earth. The unanticipated announcement of Sputnik 1's success precipitated the Sputnik crisis in the United States and ignited the so-called Space Race within the Cold War. Sputnik 2 was launched on November 3, 1957 and carried the first living passenger into orbit, a dog named Laika.5 In May, 1946, Project RAND had released the Preliminary Design of a Experimental World-Circling Spaceship, which stated, "A satellite vehicle with appropriate instrumentation can be expected to be one of the most potent scientific tools of the Twentieth Century.6 The United States had been considering launching orbital satellites since 1945 under the Bureau of Aeronautics of the United States Navy. The United States Air Force's Project RAND eventually released the above report, but did not believe that the satellite was a potential military weapon; rather, they considered it to be a tool for science, politics, and propaganda. In 1954, the Secretary of Defense stated, "I know of no American satellite program."7 On July 29, 1955, the White House announced that the U.S. intended to launch satellites by the spring of 1958. This became known as Project Vanguard. On July 31, the Soviets announced that they intended to launch a satellite by the fall of 1957. Following pressure by the American Rocket Society, the National Science Foundation, and the International Geophysical Year, military interest picked up and in early 1955 the Air Force and Navy were working on Project Orbiter, which involved using a Jupiter C rocket to launch a satellite. The project succeeded, and Explorer 1 became the United States' first satellite on January 31, 1958. In June 1961, three-and-a-half years after the launch of Sputnik 1, the Air Force used resources of the United States Space Surveillance Network to catalog 115 Earth-orbiting satellites. The largest artificial satellite currently orbiting the Earth is the International Space Station. Space Surveillance Network The United States Space Surveillance Network (SSN) has been tracking space objects since 1957 when the Soviets opened the space age with the launch of Sputnik I. Since then, the SSN has tracked more than 26,000 space objects orbiting Earth. The SSN currently tracks more than 8,000 man-made orbiting objects. The rest have re-entered Earth's turbulent atmosphere and disintegrated, or survived re-entry and impacted the Earth. The space objects now orbiting Earth range from satellites weighing several tons to pieces of spent rocket bodies weighing only 10 pounds. About seven percent of the space objects are operational satellites (i.e. ~560 satellites), the rest are space debris.10 USSTRATCOM is primarily interested in the active satellites, but also tracks space debris which upon reentry might otherwise be mistaken for incoming missiles. The SSN tracks space objects that are 10 centimeters in diameter (baseball size) or larger. Non-Military Satellite Services There are three basic categories of non-military satellite services: Fixed Satellite Service Fixed satellite services handle hundreds of billions of voice, data, and video transmission tasks across all countries and continents between certain points on the earth’s surface. Mobile Satellite Systems Mobile satellite systems help connect remote regions, vehicles, ships, people and aircraft to other parts of the world and/or other mobile or stationary communications units, in addition to serving as navigation systems. Scientific Research Satellite (commercial and noncommercial) Scientific research satellites provide us with meteorological information, land survey data (e.g., remote sensing), Amateur (HAM) Radio, and other different scientific research applications such as earth science, marine science, and atmospheric research. Category:Modern Category:Technology Category:Satellites